Methods and apparatus for sending fast negative acknowledgements (NACKs)

Abstract

Methods and apparatus are provided for quick recovery of missed packets after a user equipment (UE) tunes back to a first network after tuning away from the first network. The UE may determine that a trigger event has occurred, and in response to the determination, modify a negative acknowledgement (NACK) timing configuration from a default configuration. Modifying the NACK timing configuration may include using an aggressive NACK timing configuration for a configurable period of time, in response to detecting a trigger event. The trigger event may include detecting missed packets after a tune back, unavailability of sufficient memory to hold packets until a gap created by missed packets may be filled, or tuning back to a network.

What is claimed is: 
     
       1. A method of wireless communication by a user equipment (UE), comprising:
 determining that a trigger event has occurred; 
 in response to the determination, modifying a negative acknowledgement (NACK) timing configuration by initializing a time period of an aggressive NACK timing configuration, wherein during the time period, NACKs for one or more missed packets are transmitted quicker relative to a default NACK timing configuration; and 
 transmitting one or more NACKs in accordance with the modified NACK timing configuration. 
 
     
     
       2. The method of  claim 1 , further comprising determining that a packet is received out of order indicating one or more missed packets, wherein determining the trigger event comprises determining that memory available to store packets received out of order has fallen below a threshold value. 
     
     
       3. The method of  claim 2 , wherein the threshold value is configurable at the UE. 
     
     
       4. The method of  claim 1 , further comprising:
 tuning back to a first network after tuning away from the first network, wherein determining the trigger event comprises determining that a packet received after tuning back to the first network is received out of order. 
 
     
     
       5. The method of  claim 1 , wherein the trigger event comprises tuning back to a first network after tuning away from the first network. 
     
     
       6. The method of  claim 1 , further comprising tuning back a first receive chain to a first network after tuning away from the first network, the first receive chain being one of at least two receive chains configured for the first network,
 wherein determining the trigger event comprises at least one of determining that the first receive chain tuned back to the first network or determining that a packet received after the tuning back is received out of order. 
 
     
     
       7. The method of  claim 1 , further comprising using a reordering timer with a value that is less than a default value of the reordering timer, during the time period of the aggressive NACK timing configuration. 
     
     
       8. The method of  claim 1 , further comprising sending one or more NACKs for one or more missed packets without waiting for a reordering timer to expire, during the time period of the aggressive NACK timing configuration. 
     
     
       9. The method of  claim 1 , further comprising during the time period of the aggressive NACK timing configuration:
 sending NACKs for one or more missed packets without waiting for a reordering timer to expire if a packet received out of order is the first packet received after tune back to a network; and 
 initializing a reordering timer with a value that is less than a default value of the reordering timer, if the packet received out of order is not the first packet received after tune back to the network. 
 
     
     
       10. The method of  claim 1 , wherein the time period is configurable at the UE. 
     
     
       11. The method of  claim 1 , wherein a value of a reordering timer used during the time period is configurable at the UE. 
     
     
       12. The method of  claim 1 , further comprising reverting to a default NACK timing configuration after expiration of the time period. 
     
     
       13. An apparatus for wireless communication, comprising:
 means for determining that a trigger event has occurred; 
 means for modifying a negative acknowledgement (NACK) timing configuration by initializing a time period of an aggressive NACK timing configuration, wherein during the time period, NACKs for one or more missed packets are transmitted quicker relative to a default NACK timing configuration; and 
 means for transmitting one or more NACKs in accordance with the modified NACK timing configuration. 
 
     
     
       14. The apparatus of  claim 13 , further comprising means for determining that a packet is received out of order indicating one or more missed packets, wherein the trigger event comprises determining that memory available to store packets received out of order has fallen below a threshold value. 
     
     
       15. The apparatus of  claim 14 , wherein the threshold value is configurable at the apparatus. 
     
     
       16. The apparatus of  claim 13 , further comprising:
 means for tuning back to a first network after tuning away from the first network, wherein the trigger event comprises determining that a packet received after tuning back to the first network is received out of order. 
 
     
     
       17. The apparatus of  claim 13 , wherein the trigger event comprises tuning back to a first network after tuning away from the first network. 
     
     
       18. The apparatus of  claim 13 , further comprising means for tuning back a first receive chain to a first network after tuning away from the first network, the first receive chain being one of at least two receive chains configured for the first network,
 wherein the trigger event comprises at least one of determining that the first receive chain tuned back to the first network or determining that a packet received after the tuning back is received out of order. 
 
     
     
       19. The apparatus of  claim 13 , further comprising means for using a reordering timer with a value that is less than a default value of the reordering timer, during the time period of the aggressive NACK timing configuration. 
     
     
       20. The apparatus of  claim 13 , further comprising means for sending one or more NACKs for one or more missed packets without waiting for a reordering timer to expire, during the time period of the aggressive NACK timing configuration. 
     
     
       21. The apparatus of  claim 13 , further comprising means for, during the time period of the aggressive NACK timing configuration,
 sending NACKs for one or more missed packets without waiting for a reordering timer to expire if a packet received out of order is the first packet received after tune back to a network; and 
 initializing a reordering timer with a value that is less than a default value of the reordering timer, if the packet received out of order is not the first packet received after tune back to the network. 
 
     
     
       22. The apparatus of  claim 13 , wherein the time period is configurable at the apparatus. 
     
     
       23. The apparatus of  claim 13 , wherein a value of a reordering timer used during the time period is configurable at the apparatus. 
     
     
       24. The apparatus of  claim 13 , further comprising means for reverting to a default NACK timing configuration after expiration of the time period. 
     
     
       25. An apparatus for wireless communication, comprising:
 at least one processor configured to:
 determine that a trigger event has occurred; 
 in response to the determination, modify a negative acknowledgement (NACK) timing configuration by initializing a time period of an aggressive NACK timing configuration, wherein during the time period, NACKs for one or more missed packets are transmitted quicker relative to a default NACK timing configuration; and 
 transmit one or more NACKs in accordance with the modified NACK timing configuration; and 
 
 a memory coupled to the at least one processor. 
 
     
     
       26. A non-transitory computer-readable medium for wireless communication by a user equipment (UE), storing instructions which when executed by at least one processor performs a method comprising:
 determining that a trigger event has occurred; 
 in response to the determination, modifying a negative acknowledgement (NACK) timing configuration by initializing a time period of an aggressive NACK timing configuration, wherein during the time period, NACKs for one or more missed packets are transmitted quicker relative to a default NACK timing configuration; and 
 transmitting one or more NACKs in accordance with the modified NACK timing configuration.